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Conference ssag::ask_ssag

Title:	Ask the Storage Architecture Group
Notice:	Check out our web page at http://www-starch.shr.dec.com
Moderator:	SSAG::TERZAN

Created:	Wed Oct 15 1986
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	6756
Total number of notes:	25276

6727.0. "using RA450s in rack mount (SW800) ???" by FIREBL::LEEDS (From VAXinated to Alphaholic) Wed May 28 1997 18:15

I was out with a Distributor yesterday meeting with a customer. The custoer 
wanted a quote for 250GB of RZ29 disk storage with HSZ50s. 

Normally, we would configure a SW800, some BA350-MBs with HSZ52s, BA356s, 
cables, power supplies, etc (or an ESA).

However, this guy insisted that the better way to configure this was three 
RA450s, rack-mounted in an SW800. His reasoning was the following:

1) the physical setup is much easier for a customer to understand (no
   guessing which drive shelves are connected to which controller, no cables 
   to deal with, no sideways mounted shelves, etc.). 

2) Limit of 4 drives per shelf - can't accidentally put too many disks on 
   a SCSI bus and have performance problems

3) Redundant power for the entire array, not just specific shelves.

I've never configured RA450s like this. Our local Storage Sales guy thinks 
it'll work, but I wanted a second opinion. 

Can/will this work ?  Is it supported ??  Any downside to doing it this way?

Thanks 

Arlan

T.R	Title	User	Personal Name	Date	Lines
6727.1		HOUNDD::BASSETT	Bill	`Wed May 28 1997 19:19`	25
	Arlan, I support on-base products, so I'm never certain what Raid Array xxx part number converts to what on-base product. I think the RA450 is made from the SW300 - and has preconfigured controllers and drives(?). If so, you have the following path: The SW300 has a rackmount version. It's called the BA355-AA. It's the SW300 without the plastic skins. You then add the SW800 mounting kit - BA35X-RA - to mount it in the SW800. (It also may NOT ship with 5 power supplies as the SW300-AA does, but power supplies are easily added.) Up to 4 BA355's can mount in the SW800. This product has been available for about 18-24 months, but the numbers shipped are somewhat low.... Is there a RA450 version? I don't know, but you could buy the SW800 and configure it with the parts you need. OK? Bill
6727.2		OTOOA::LAVIGNE		`Wed May 28 1997 22:54`	17
	Yes it will work the only negative is that the fans in the back of the 450's will be some work to get at if you put 3 450's into an SW800. Another negative is that when your customer wants to upgrade to Ultra-SCSI they will have to change cabs as well as the SW800. If they go with shelves they will be able to upgrade to the new M shelf and still use the older shelves of disks with the new controller. The SW800 config will have cables to controllers as well as shelves. Using the 450's the only cables are to the controllers. The 450's limit you to 24 drives per controller pair while the shelf solution will allow 36 drives per controller pair. I doubt you would notice any performance degradation if your Raid sets are configured properly with 24 drives or 36. Both will work and no one is better than the other, they are just different. Regards, JP Lavigne
6727.3	no need for SW800 in with RA450	TROOA::MSCHNEIDER	schneiderma@mail.dec.com	`Fri May 30 1997 02:39`	11
	Why bother with the SW800 cabinet .... use a standard 19" RETMA rack if you plan on rackmount RAID Array 450. Part number DS-SWXRA-W4 RAID Array 450 Rackmount Storage Subsystem JP brings up a good point about UltraSCSI upgradability limitations. It is however a neat and tidy solution in terms of usability as pointed out in the base note. It is also cheaper to buy the RA450 then the sum of the parts (e.g. BA350-MB, HSZ50, BA356, cables, power supplies, etc)